In one embodiment, a particle sensor on or in a vehicle is provided. The laser particle sensor comprises an optical system; a processing system coupled to the optical system; wherein the optical system is configured to transmit one or more laser light beams to detect particles in a volume of freestream fluid, and to have the one or more light beams terminate on a portion of the vehicle on which the optical system is mounted; and wherein the optical system is configured to receive a backscattered portion of the one or more laser light beams transmitted by the optical system.